Most motorized wheelchairs use a manual controller of the joystick type. This joystick controller involves a manually-engageable control lever which is mounted on the arm of the wheelchair so as to be readily accessible to the occupant, with the control lever being normally maintained in an upright neutral position by biasing arrangements such as springs. The control lever or joystick is then pushed forwardly or rearwardly to respectively energize the drive wheels to carry out forward or rearward driving of the wheelchair, with the joystick being manually urged either rightwardly or leftwardly to cause corresponding rightward or leftward steering of the wheelchair, this causing a corresponding adjustment in the motors driving the right and left wheels.
The conventional joystick controller is normally of the inductive type. That is, the lower end of the joystick mounts a coil which is positioned between four stationary coils arranged in a generally rectangular pattern, which four stationary coils depict the forward, rearward, rightward and leftward directions. Movement of the joystick and its associated coil creates, in the stationary coils to which the moving coil approaches, appropriate voltage signals which are then transmitted to the wheelchair controller. This in turn appropriately drives the motors associated with the right and left drive wheels. Arrangements of this general type are well known and have been utilized for many years.
However, this inductive-type joystick controller has been observed to create problems of inadvertent wheelchair movement due to stray EMI or RFI signals. Such stray signals are picked up by the controller, which effectively acts as an antenna, and can cause false signals to be fed to the controller of the wheelchair, which in turn then provides undesired signals to the drive motors to cause undesired driving and/or steering. This is becoming an even greater and more common problem with the highly increased usage of equipment which generates radio frequency or electromagnetic signals, such as walkie talkies, cellular telephones and the like.
Accordingly, it is an object of this invention to provide an improved joystick controller for a motorized wheelchair, which joystick controller overcomes the above disadvantages by eliminating the sensitivity to EMI and RFI pickup, which eliminates any need for moving or contacting electrical parts, which can be of a rugged and heavy-duty design which is operable over a wide range of operating temperatures, and which provides improved convenience, reliability and safety for the wheelchair occupant.
More specifically, the present invention relates to an improved motorized wheelchair wherein the joystick controller employs a fiber-optic arrangement for sensing joystick movement, which fiber-optic arrangement generates output light signals of variable intensity in proportion to the displacement of the joystick movement, which output light signals are converted to electrical signals and supplied to a conventional wheelchair controller for controlling the driving of the drive wheels.
In a preferred embodiment, the improved joystick controller for the motorized wheelchair employs a single light source which supplies light through fiber-optic cables for discharge against a pair of reflective surfaces which are associated with a pair of followers, which followers respond to the two planes of movement of the joystick. A fiber-optic pickup cable is associated with each reflective surface, with the intensity of the light received by the pickup cable being a function of the position of the reflective surface relative thereto. The intensity of the light supplied to the pickup cable is then transmitted to a light detector which converts the light signal to an electrical signal, the magnitude of which is proportional to the intensity of the light signal. The electrical signal is then transmitted to a controller and processed in a generally conventional manner for controlling the driving of the wheelchair wheels.